Existing machines, for example, those described in U.S. Pat. Nos. 4,478,223, 4,395,255 and 4,516,761, and United Kingdom Patent No. 1177241 include a first feed roller mounted above and extending at right angles to an output roller. The paper is folded along a preformed weakened fold line, which may be either pre-creased, scored or perforated, as it passes between the upper feed roller and the lower output roller. The machine may also include some form of guide arrangement, to assist in forming the fold, located between the upper and lower rollers.
These machines have a number of disadvantages. They will only operate satisfactorily if the paper used is provided with an already-weakened fold line. This in itself leads to difficulties in that the tension applied to the paper in drawing it through the machine may cause it to burst or tear, particularly where the fold line is perforated. Furthermore, such machines are, in general capable only of providing a central fold.
Also, because it is necessary with existing machines to pre-perforate or pre-score the paper web, it has not, in general, been possible to use such machines to fold multi-sheet stationery. In addition, such machines can only be used to form a right-hand or a left-hand fold. A change from one type of fold to the other requires substantial reconstruction of the machine.
In accordance with the first aspect of the invention, there is provided apparatus for forming a longitudinally-extending fold in a web of paper, the apparatus comprising:
a paper feed arrangement for driving the web through said apparatus, the said paper feed arrangement including a support extending transversely of the web and mounting a pair of drive members engageable with opposite longitudinal edges of the web; and
paper folding means disposed below, and downstream of, said paper feed arrangement, the paper folding means including a pair of fold-plates defining a narrow gap through which the web passes to form a fold and a pair of output rollers resiliently biased into engagement with one another, between which the web passes on leaving said fold-plates, the gap defined by the fold plates and by the output rollers extending at right angles to the support;
said support carrying said drive members being movable in a transverse direction to alter the position of the web relative to the fold-plates and, hence, to alter the transverse position of the fold formed in the web.
In accordance with a further aspect of the invention there is provided apparatus for forming a longitudinally-extending fold in a web of paper, the apparatus comprising:
a paper feed arrangement for driving the web through said apparatus;
paper folding means disposed below, and downstream of, said paper feed arrangement, the paper folding means including a pair of fold-plates defining a narrow gap through which the web passes to form a fold and a pair of output rollers resiliently biased into engagement with one another, between which the web passes on leaving said fold-plates; and
guide means extending between said paper feed arrangement and said paper folding means for guiding the web into the fold-plates, said guide means including a member defining a V-shape having edges extending from position spaced apart by a distance greater than the width of the web and immediately below the paper feed arrangement, to a vertex substantially immediately above the fold-plates and disposed centrally thereof.
In accordance with a still further aspect of the invention there is provided apparatus for forming a longitudinally-extending fold in a web of paper, the apparatus comprising:
a paper feed arrangement for driving the web through said apparatus, the said paper feed arrangement including a support extending transversely of the web and mounting a pair of tractor drives having rotary members which, in use, engage the margins of the web and which are rotatable to drive the web in a downstream direction;
paper folding means disposed below, and downstream of, said paper feed arrangement, the paper folding means including a pair of fold-plates defining a narrow gap through which the web passes to form a fold and a pair of output rollers resiliently biased into engagement with one another, between which the web passes on leaving said fold plates, the gap defined by the fold-plates and by the output rollers extending at right angles to the support; and
first and second motors, coupled to said tractor drives and to said output rollers respectively, and control means coupled to said first and second motors and operable to actuate said motors to drive the tractor drives and output rollers simultaneously.